heterodyne

Etymology
From.

Adjective

 * 1) Of two oscillations: having two slightly different frequencies such that, when combined, they produce a beat

Noun

 * 1) The beat so produced
 * 2) Either the sum or difference of the two oscillations

Derived terms

 * supersonic heterodyne receiver

Verb

 * 1) To produce heterodyne interference in a radio
 * 2) To change the frequency of a signal by such a process